While the clinical utility of circulating tumor cells (CTCs) for the management of many different types of cancers are being realized, the challenge in selecting them from peripheral blood and enumerating them is daunting due to the exceedingly high numbers of spectator cells (erythrocytes and leukocytes) and the low abundance of the CTCs (<I0/7.5 ml of whole blood). The goal of this project is to fabricate and evaluate the performance of an exciting new technology for the analysis of CTCs. The technology consists of a fluidic cartridge made from conventional plastics, such as Plexiglas, through micro-replication that can select CTCs from blood in under 20 min with recoveries >go%. The cartridge will also enumerate the selected CTCs using a non-labeling process that requires no optical equipment;enumeration is accomplished using a conductivity sensor comprised of a pair of electrodes situated orthogonal to the output channel of the device that provides nearly 100% sampling and detection efficiency. The cartridge will also direct the CTCs into a small chamber, stain the cells with antibodies labeled with a fluorescent dye and characterize them using fluorescence microscopy without scanning. The fluidic cartridge will possess a footprint the sue of a microscope slide.